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There has been a lot of breathless coverage of 3D Printing, more accurately called additive manufacturing. In the supply chain realm is has been speculated that additive manufacturing could be able to transform the spare parts supply chain. The idea is that instead of carrying a plethora of slow moving parts across a network of warehouses, these warehouses could just manufacture the parts as needed.

But ARC's expert on Additive Manufacturing, Sal Spada, believes the potential is being over-hyped. Further, at ARC's annual automation forum held in Orlando, Florida, attendees heard perspectives on 3D Printing and Additive Manufacturing from two of the world’s leading experts in the field. The message was clear regarding additive manufacturing, "if you are considering additive manufacturing on the horizon as as part of a manufacturing strategy then you better start now." The technology limitations and required process knowledge are nontrivial.

Charles Gilman, for example, has been involved in with GE Global Research's initiative in additive manufacturing for over 15 years. However, the public awareness factor has increased considerably since 2011 when GE's aerospace division made a huge commitment to using additive manufacturing processes to produce the LEAP fuel nozzle for their jet engines. According to Charles Gilman, the fuel nozzle was selected as a pragmatic entre for GE to incorporate additive manufacturing into the production processes. The fuel nozzle is an ideal component. In the jet engine there are 19 fuel nozzles of where a failure in one or multiple nozzles would not be catastrophic. However, the cost and complexity of manufacturing a fuel nozzle using traditional subtractive processes - machining raw material down to its desired shape - is expensive and places limits on the design of the nozzle.

The journey for GE was not overnight, as it took over 10 years to refine the company’s additive manufacturing process. Using a laser sintering process from the outset the challenges were multifold. In additive manufacturing the structural properties of the finished product are highly dependent upon the formulation of the metal powder and the operating parameters of the laser sintering machine. This required seminal research in both these areas to be accomplished simultaneously. There is clearly a business case to consider additive manufacturing in a very select number of production parts, however the development of process knowledge can be a tremendous investment in time and resources.

One challenge is that additive manufacturing is inherently less accurate than subtractive manufacturing. In traditional subtractive/machining manufacturing the CAD models remain accurate to 10-3 thousandths (inch) whereas the computer software files associated with additive manufacturing result in models with only 2 thousandths(inch) in accuracy. In practice, the tolerances on a part produced using additive manufacturing process is only 5 thousandths (inch) which implies that additional finishing processes will be required. Inspecting of dimensional accuracies can be highly challenging. In some cases CT scanning can be used, but this is a significant investment in both equipment and training for the manufacturing environment.

There are numerous other challenges that require additional research to ensure that a product can be produced consistently. Monitoring of the process dynamically is not currently available for additive manufacturing whereas in conventional machining this is relatively standard. Basically, an additive manufacturing process could result in scrapping a part that took hours to produce because during the production the process was out of control.

Further, 3D Printing has advanced furthest for making plastic and metal parts. For other applications, like making printed circuit boards, this technology is only in the early stages of proving its viability.

Overall, the challenges in additive manufacturing are surmountable, but it will take a commitment that for some applications could take up to a decade.